Acrylic film, method for producing same, laminate film, laminated injection molded article, and method for producing rubber-containing polymer

ABSTRACT

An acrylic film having few fish eyes and a method for producing latex of an acrylic rubber-containing polymer having low amounts of coarse particles, excellent filtering properties, and low filter clogging frequency during a filtration step for removing foreign substances are provided. An acrylic film containing an acrylic rubber-containing polymer (G) has a thickness of 30 to 300 μm, wherein the number of fish eyes that are 0.001 mm 2  or greater in size is 130/m 2  or fewer when a section having a light transmission rate of 75% or less for light having a wavelength of 400 to 1100 nm was detected as a fish eye.

TECHNICAL FIELD

The present invention relates to an acrylic film, a laminate film, and alaminated injection molded article. The present invention also relatesto a method for producing a rubber-containing polymer suitable for usein a film.

BACKGROUND ART

According to emulsion polymerization, the polymerization reactiongenerally occurs within micelles of a surfactant that are provided by asurfactant. The polymer produced in accordance with a progress of thepolymerization is not soluble or hardly soluble in water, but due to anaction of a surfactant, it is stably dispersed as fine particles in anaqueous medium without being separated or precipitated from the aqueousmedium. Such polymer dispersion is referred to as latex.

If polymer latex is produced by emulsion polymerization, coarseparticles with a size of 10 to 100 μm or so in which polymer particlesare aggregated are produced in a large amount. Unlike a scale adhered toan inner wall of a reactor or a stirring wall, the coarse particles areincluded in latex in a dispersed state so that it is incorporated withlatex to a step after the polymerization. Once the coarse particles areincorporated in a product, they are known to cause defects that arereferred to as “protrusions” (hereinbelow, also referred to as a “fisheye”). For an optical application or an application requiring adecorative property, in particular, coarse particles with a size ofseveral tens of μm or higher become a cause of defects in the product.As such, it is desired to suppress generation of coarse particles with asize of several tens of μm or higher that are produced duringpolymerization and also to remove the produced coarse particles.

The step for filtering polymer latex is to remove coarse particles thatare generated during polymerization from latex or to remove foulsubstances that are incorporated in a raw polymer material or introducedfrom an outside during polymerization, and it is an essential step forreducing foreign substances. Hereinbelow, the coarse particles and foulsubstances are collectively referred to as “foreign substances”. When afilter medium mesh for filtering is decreased to reduce foreignsubstances, the filter medium is easily clogged by the foreignsubstances, in particular, the coarse particles. Accordingly, thelifetime of a filter medium is shortened so that the production speedinevitably needs to be slowed down and the filter medium replacementfrequency is increased. Namely, decreasing the size of a filter mediummesh to reduce foreign substances has a problem that productivity forlatex polymer is lowered and also it is no longer possible to continuestable production.

In other words, for producing polymer latex, reducing foreign substancesand having simultaneously stable production and enhanced productionefficiency are a difficult task to achieve. However, it is stronglydesired to have both of them.

According to Patent Document 1, a method of mixing a monomer forpolymerization with water and a surfactant and supplying them as anemulsion to a reactor is suggested as a method of suppressing scaleduring emulsion polymerization. In Patent Document 1, there is adescription about an effect of reducing scale which does not passthrough 60 mesh among scales adhered on an inner wall of a reactor and astirring wing and scales contained in latex. However, no mention is maderegarding reduction of coarse particles as a cause of protrusions andthe filtering property of latex, and thus the problems still remain. InPatent Document 2, a method of reducing acetone insoluble particles witha size of at least 55 μm, which become a cause of fish eye in an acrylicfilm, is suggested. According to Patent Document 2, fish eyes having asize of 0.4 mm×0.5 mm or more in a film with a thickness of 50 μm werelowered by reducing acetone insoluble particles with a size of at least55 μm. However, as there is no mention about fish eyes with a smallersize, it cannot be said that the method is sufficient by itself.Furthermore, in Patent Document 3, a method of removing an aggregate asa cause of fish eye by a specific filtering method is suggested.According to Patent Document 3, small fish eyes with a size of at least25 μm are also reduced in an acrylic film with a thickness of 80 μm.However, as a standard for detecting fish eyes is loose, that is, havinga transmission ratio of 50% or less, it is expected to have many fisheyes if the measurement is made with a transmission ratio of 75%.Furthermore, when a filtering mesh is 1 μm like Patent Document 3, thefiltering medium is easily clogged so that production efficiency may belowered. For further reducing fish eyes, it is essential to suppressgeneration of coarse particle as a cause of fish eye and reduce meshsize during filtration step. It is also essential to establish a methodfor producing latex with a good filtering property to reduce mesh size.

CITATION LIST Patent Document

Patent Document 1: JP 05-295050 A

Patent Document 2: JP 2003-128735 A

Patent Document 3: JP 2009-270028 A

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide an acrylic film withfew fish eyes. Another object of the present invention is to provide amethod for producing polymer latex to be a raw material of the film inwhich the amount of coarse particles is extremely low, and whichexhibits an excellent filtering property and has a low filter cloggingfrequency during a filtration step for removing foreign substances.

Means for Solving Problem

As a result of intensive studies, the inventors of the present inventionfound that the aforementioned problems can be solved by adopting aspecific production method for producing polymer latex. The presentinvention [1] to [14] shown below was completed accordingly.

[1] An acrylic film containing an acrylic rubber-containing polymer (G)and having a thickness of 30 to 300 μm, in which the number of fish eyesthat are 0.001 mm² or greater in size is 130/m² or fewer per 1 m² of theacrylic film when a section having a light transmission ratio of 75% orless for light having a wavelength of 400 to 1100 nm is detected as afish eye by using a surface inspection device.

[2] The acrylic film described in above [1] in which acetone insolublesamount W1 is 5 to 70% by mass and acetone solubles amount W2 is 95 to30% by mass in the acrylic film (with the proviso that the sum of W1 andW2 is 100% by mass), the ratio of the alkyl acrylate component in theacetone insolubles is 20% by mass or more, and the ratio of the alkylmethacrylate component in the acetone solubles is 50% by mass or more.

[3] The acrylic film described in above [2] in which the total ratio ofthe alkyl methacrylate component and the aromatic vinyl compoundcomponent is 80 to 0% by mass in the acetone insolubles and the totalratio of the alkyl acrylate component and the aromatic vinyl compoundcomponent is 50 to 0% by mass in the acetone solubles.

[4] The acrylic film described in any one of above [1] to [3] in whichthe acrylic rubber-containing polymer (G) is a polymer produced by amulti-stage polymerization step including the following steps (1) and(2):

(1) a polymerization step in which a first emulsion having a monomermixture (a) containing 20% by mass or more of alkyl acrylate emulsifiedin water is supplied to a polymerization vessel to proceed with thefirst stage polymerization, and

(2) a polymerization step in which a second emulsion having a monomermixture (b) containing 50% by mass or more of alkyl methacrylateemulsified in water is supplied to the polymerization vessel after thefirst polymerization step to proceed with the final stagepolymerization.

[5] A method for producing an acrylic rubber-containing polymer (G) usedfor an acrylic film, the method including a multi-stage polymerizationstep including the following steps (1) and (2):

(1) a polymerization step in which a first emulsion having a monomermixture (a) containing 20% by mass or more of alkyl acrylate emulsifiedin water is supplied to a polymerization vessel to proceed with thefirst stage polymerization, and

(2) a polymerization step in which a second emulsion having a monomermixture (b) containing 50% by mass or more of alkyl methacrylateemulsified in water is supplied to the polymerization vessel after thefirst polymerization step to proceed with the final stagepolymerization.

[6] The method for producing an acrylic rubber-containing polymer (G)described in above [5], in which a polymerization step with at least onestage is included between the step (1) and the step (2).

[7] The method for producing an acrylic rubber-containing polymer (G)described in above [5], in which a number average particle diameter of adispersion phase is 300 μm or less for the first emulsion and the secondemulsion, respectively.

[8] A method for producing an acrylic film, the method including a stepof obtaining powder of an acrylic rubber-containing polymer (G) afterfiltration by passing latex of an acrylic rubber-containing polymer (G)produced by the method described in [5] through a filtering medium with1 to 100 μm mesh and a step of producing a film by melt extrusion of anacrylic resin composition containing the powder of the acrylicrubber-containing polymer (G) from a T die.

[9] A method for producing the acrylic film described in any oneselected from the above [1] to [4], the method including a step ofobtaining powder of an acrylic rubber-containing polymer (G) afterfiltration by passing latex of an acrylic rubber-containing polymer (G)produced by the method described in [5] through a filtering medium with1 to 100 μm mesh and a step of producing a film by melt extrusion of anacrylic resin composition containing the powder of the acrylicrubber-containing polymer (G) from a T die.

[10] A method for producing an acrylic film, the method including a stepof producing a film by melt extrusion of an acrylic resin compositioncontaining an acrylic rubber-containing polymer (G), which is producedby the method described in [5], from a T die and a step of sandwichingthe film between two pieces selected from a metal roll, a non-metalroll, and a metal belt.

[11] A method for producing the acrylic film described in any oneselected from the above [1] to [4], the method including a step ofproducing a film by melt extrusion of an acrylic resin compositioncontaining an acrylic rubber-containing polymer (G), which is producedby the method described in [5], from a T die and a step of sandwichingthe film between two pieces selected from a metal roll, a non-metalroll, and a metal belt.

[12] A laminate film formed by laminating the acrylic film described inany one selected from the above [1] to [4] and a layer of at least oneresin selected from a thermoplastic resin, a thermosetting resin, and aphotocurable resin.

[13] A laminated injection molded article formed by laminating theacrylic film described in any one selected from the above [1] to [4] onan injection molded article.

[14] A laminated injection molded article formed by laminating thelaminate film described in [12] on an injection molded article.

Effect of the Invention

According to the present invention, a film with few fish eyes isprovided. Also provided by the present invention is a method forproducing polymer latex to be a raw material of the film in which theamount of coarse particles is extremely low, and which exhibits anexcellent filtering property and has a low filter clogging frequencyduring a filtration step for removing foreign substances.

MODE(S) FOR CARRYING OUT THE INVENTION

<Acrylic Film>

The acrylic film of the present invention is an acrylic film containingthe acrylic rubber-containing polymer (G) and it has a thickness of 30to 300 μm. Further, the number of fish eyes that are 0.001 mm² orgreater in size is 130/m² or fewer per 1 m² of the acrylic film when asection having a light transmission ratio of 75% or less for lighthaving a wavelength of 400 to 1100 nm is detected as a fish eye by usinga surface inspection device.

The thickness of the acrylic film of the present invention is 30 to 300μm. As the thickness of the acrylic film is 30 μm or more, it ispossible to protect a base for a laminated injection molded article sothat a molded article to be obtained can be given with sufficient depthfeel. In addition, as the thickness of the acrylic film is 300 μm orless, rigidity suitable for insert- and in-mold molding can be obtained.Furthermore, from these points of view, the thickness of the acrylicfilm is more preferably 50 μm or more and 200 μm or less.

In the present invention, a section having a transmission ratio of 75%or less for light having a wavelength of 400 to 1100 nm is detected as afish eye. Since the number of fish eyes is 130 or fewer per 1 m² of afilm even when small defects that are detected according to suchstringent conditions are counted as a fish eye, the acrylic film of thepresent invention has a high-level printing property. Specifically, theacrylic film of the present invention has less printing losses even whengravure printing such as pale color wood grain pattern under a lowerprinting pressure and metallic and jet-black printing, by which printinglosses particularly tend to occur, are performed, and has a high levelprinting property that is never obtained with an acrylic film in which arubber-containing polymer known in a related art is used as a rawmaterial.

As a surface inspection device, B-LSC-6276-MR (manufactured by MEC Co.,Ltd.) is used.

[Acrylic Rubber-Containing Polymer (G)]

The acrylic film of the present invention contains the acrylicrubber-containing polymer (G). The acrylic film has, by containing theacrylic rubber-containing polymer (G), suitable flexibility in additionto high transparency and weather resistance that are intrinsic to anacrylic film, and thus it has excellent processability for thermallamination, or the like.

The acrylic rubber-containing polymer (G) is a polymer which contains anacrylic rubber component in an inner layer and a hard component in anouter layer. The acrylic rubber is rubber obtained by polymerizing alkyl(meth)acrylate or a mixture containing it at 50% by mass or more.

[Method for Producing Acrylic Rubber-Containing Polymer (G)]

The acrylic rubber-containing polymer (G) is preferably produced by anemulsion polymerization which has a multi-stage polymerization stepincluding the following steps (1) and (2):

(1) a polymerization step in which a first emulsion having a monomermixture (a) containing 20% by mass or more of alkyl acrylate emulsifiedin water is supplied to a polymerization vessel to proceed with thefirst stage polymerization, and

(2) a polymerization step in which a second emulsion having a monomermixture (b) containing 50% by mass or more of alkyl methacrylateemulsified in water is supplied to the polymerization vessel after thefirst polymerization step to proceed with the final stagepolymerization,

The method for producing latex of the acrylic rubber-containing polymer(G) includes a step of emulsion polymerization of the monomer mixture(a) and a step of emulsion polymerization of the monomer mixture (b). Ifnecessary, a polymerization step with one or more stages in which themonomer mixture (c) or the like is subjected to emulsion polymerizationmay be included between those emulsion polymerization steps. Since theproduction is achieved by emulsion polymerization with two or morestages and a monomer mixture is supplied as an emulsion to apolymerization vessel during polymerization at the first stage and alsothe final stage, production of coarse particles in finally-obtainedlatex is suppressed so that a film with few fish eyes can be produced.

Furthermore, it is also possible to include a step for emulsionpolymerization of the monomer mixture(s) to have polymer Tg of 70 to120° C. before the polymerization of the monomer mixture (a).

Hereinbelow, the method for producing latex of the acrylicrubber-containing polymer (G) of the present invention is described indetail. The monomer components are described first and thepolymerization method is described later. As described herein,“(meth)acryl” means either “acryl” or “methacryl”. Furthermore, a“monomer mixture” means a monomer of one type or two types.

[Monomer Mixture (a) and Rubber Polymer (A)]

The monomer mixture (a) is a monomer mixture which contains alkylacrylate at 20% by mass or more on the basis of the total amount of 100%by mass, and it is a monomer mixture to be a raw material of the firststage. According to the first polymerization step for polymerizing themonomer mixture (a) as a raw material, the rubber polymer (A) isproduced.

Examples of the alkyl acrylate (hereinbelow, it may be referred to asthe “monomer (a1)”) include methyl acrylate, ethyl acrylate, propylacrylate, n-butyl acrylate, 2-ethylhexyl acrylate and n-octyl acrylate.Among them, n-butyl acrylate is preferable. They may be used eithersingly or in combination of two or more types.

Examples of the monomer other than alkyl acrylate in the monomer mixture(a) include alkyl methacrylate (hereinbelow, it may be referred to asthe “monomer (a2)”), a monomer having one double bond which cancopolymerize with them (hereinbelow, it may be referred to as the“monofunctional monomer (a3)”), and a polyfunctional monomer(hereinbelow, it may be referred to as the “polyfunctional monomer(a4)”).

Examples of the alkyl methacrylate include those in which the alkylgroup is either linear or branched. Specific examples of the alkylmethacrylate include methyl methacrylate, ethyl methacrylate, propylmethacrylate and n-butyl methacrylate. They may be used either singly orin combination of two or more types.

Examples of the monofunctional monomer (a3) include acrylic monomerssuch as lower-alkoxy acrylate, cyanoethyl acrylate, acrylamide, and(meth)acrylic acid; aromatic vinyl monomers such as styrene oralkyl-substituted styrenes; and vinyl cyanide monomer such asacrylonitrile or methacrylonitrile. They may be used either singly or incombination of two or more types.

As for the polyfunctional monomer (a4), a cross-linkable monomer havingtwo or more copolymerizable double bonds in one molecule can bementioned. Specific examples are as follows: di(meth)acrylate alkyleneglycol such as ethylene glycol di(meth)acrylate, 1,3-butylene glycoldi(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, or propyleneglycol di(meth)acrylate; polyvinylbenezene such as divinylbenzene ortrivinylbenzene; a cyanurate monomer such as triallyl cyanurate ortriallyl isocyanurate, α,β-unsaturated acid such as allyl methacrylate,or allyl, methallyl, or crotyl ester of dicarboxylic acid. They may beused either singly or in combination of two or more types.

Content of the alkyl acrylate in the monomer mixture (a) is preferably20 to 99.9% by mass, and more preferably 30 to 99.9% by mass. Content ofthe alkyl methacrylate in the monomer mixture (a) is preferably 0 to69.9% by mass. Content of the monofunctional monomer (a3) in the monomermixture (a) is preferably 0 to 20% by mass. Content of thepolyfunctional monomer (a4) in the monomer mixture (a) is preferably 0.1to 10% by mass.

Glass transition temperature (hereinbelow, referred to as “Tg”) of therubber polymer (A) is preferably 25° C. or less from the viewpoint offlexibility for use in a film or the like, for example. Preferably, itis 0 to −60° C. In the present invention, Tg indicates a value which iscalculated from FOX's equation by using the values described in PolymerHand Book (J. Brandrup, Interscience, 1989). Furthermore, the content ofthe rubber polymer (A) in the acrylic rubber-containing polymer (G) ispreferably 5 to 70% by mass from the viewpoint of film forming propertyof the acrylic rubber-containing polymer (G) for use in a film or thelike, for example.1/(273+Tg)=Σ(wi/(273+Tgi))

In the above formula, Tg represents glass transition temperature (° C.)of a copolymer, wi represents mass fraction of monomer i, and Tgirepresents glass transition temperature (° C.) of a homopolymer which isobtained by polymerization of the monomer i.

[Monomer Mixture (b)]

The monomer mixture (b) is a monomer mixture which contains alkylmethacrylate at 50% by mass or more on the basis of the total amount of100% by mass. The monomer mixture (b) is a monomer mixture to be a rawmaterial of the final stage, and it constitutes the outermost layer ofthe acrylic rubber-containing polymer (G). Tg of the polymer consistingonly of the monomer mixture (b) is preferably 70 to 120° C., and morepreferably 80 to 100° C. As for the alkyl methacrylate in the monomermixture (b), at least one monomer which has been exemplified as “themonomer (a2)” in the explanations of the monomer mixture (a) can beused. As for the monomer other than alkyl methacrylate in the monomermixture (b), alkyl acrylate and a monomer having one double bond whichcan copolymerize with it (hereinbelow, it may be referred to as the“monofunctional monomer (b3)”) can be mentioned. As for the alkylacrylate, at least one monomer which has been exemplified as “themonomer (a1)” can be used. As for the monofunctional monomer (b3), atleast one monomer which has been exemplified as “the monofunctionalmonomer (a3)” can be used.

Content of the alkyl methacrylate in the monomer mixture (b) is 50 to100% by mass, preferably 51 to 100% by mass, and even more preferably 60to 100% by mass. Content of the alkyl acrylate in the monomer mixture(b) is preferably 0 to 20% by mass. Content of the monofunctionalmonomer (b3) in the monomer mixture (b) is preferably 0 to 49% by mass,and more preferably 0 to 40% by mass.

The use amount of the monomer mixture (b) in the total amount of 100% bymass of a monomer mixture which is used for the entire steps of thepolymerization method of the present invention is, from the viewpoint ofthe film forming property of the acrylic rubber-containing polymer (G)for use in a film or impact resistance of a film obtained by using theacrylic rubber-containing polymer (G) for use as an impact strengthmodifier, for example, preferably 30 to 95% by mass.

[Monomer Mixture (c)]

According to the present invention, a step for emulsion polymerizationof the monomer mixture (c) may be included between the step forproducing the rubber polymer (A) by polymerization of the monomermixture (a) and the step for polymerizing the monomer mixture (b) in thepresence of the rubber polymer (A). Examples of the monomer (c) includea mixture containing 9.9 to 90% by mass of alkyl acrylate, 0 to 90% bymass of alkyl methacrylate, 0 to 20% by mass of other monomer having onedouble bond copolymerizable with them, and 0.1 to 10% by mass of apolyfunctional monomer. As for the “other monomer” and the“polyfunctional monomer” that are used herein, the monofunctionalmonomer (a3) and the polyfunctional monomer (a4) which have beendescribed above can be exemplified.

The step for emulsion polymerization of the monomer mixture (c) can beperformed with two or more stages. When the polymerization is performedwith two or more stages, composition of the monomer mixture (c) may bethe same or different from each other. Furthermore, the monomer mixture(c) may contain a surfactant, and it is also possible to mixadditionally with water and supply as an emulsion to a polymerizationvessel after stirring.

[Successive Multi-Stage Emulsion Polymerization]

Examples of a method for producing the acrylic rubber-containing polymer(G) include successive multi-stage emulsion polymerization.

As for the method for producing the acrylic rubber-containing polymer(G) by successive multi-stage emulsion polymerization, there is a methodin which the monomer mixture (a) for obtaining the rubber polymer (A),water, and a surfactant are admixed with one another, supplied as anemulsion to a polymerization vessel, and polymerized, the monomermixture (c) is supplied to the polymerization vessel and polymerizedtherein, and the monomer mixture (b), water, and a surfactant areadditionally admixed with one another, supplied as an emulsion to thepolymerization vessel, and polymerized. Meanwhile, the step forsupplying the monomer mixture (c) to a polymerization vessel is a stepwhich is performed as required.

The polymer product obtained by using the acrylic rubber-containingpolymer (G) which has been produced by the aforementioned method has anadvantage of having fewer protrusions. When the polymer product is afilm, in particular, it is advantageous in that there are only few fisheyes.

Examples of the surfactant used for production by successive multi-stageemulsion polymerization include an anionic, a cationic, and a non-ionicsurfactant. They may be used either singly or in combination of two ormore types. Examples of the anionic surfactant include rosin soap;potassium oleate; carboxylate salt such as sodium stearate, sodiummyristate, sodium N-lauroyl sarcosinate, or dipotassium alkenylsuccinate; sulfate ester salt such as sodium lauryl sulfate; sulfonatesalt such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, and sodium alkyldiphenyl ether disulfonate; phosphate estersalt such as sodium polyoxyethylene alkyl phenyl ether phosphate orsodium polyoxyethylene alkyl ether phosphate. Specific examples of acommercial product of an anionic surfactant include those with thefollowing trade names: ELEMINOL NC-718 manufactured by Sanyo ChemicalIndustries, Ltd., PHOSPHANOL LS-529, PHOSPHANOL RS-610NA, PHOSPHANOLRS-620NA, PHOSPHANOL RS-630NA, PHOSPHANOL RS-640NA, PHOSPHANOL RS-650NA,and PHOSPHANOL RS-660NA manufactured by TOHO Chemical Industry Co.,Ltd., and LATEMUL P-0404, LATEMUL P-0405, and LATEMUL P-0406, LATEMULP-0407 manufactured by Kao Corporation.

Examples of the method for preparing an emulsion by mixing a monomermixture, water, and a surfactant include the following methods (1) to(3). (1) A method of adding a monomer mixture to water followed byaddition of a surfactant and sufficient stirring, (2) a method of addinga surfactant to water followed by addition of a monomer mixture andsufficient stirring, and (3) a method of adding a surfactant to amonomer mixture followed by addition of water and sufficient stirring.

As for the mixing device for preparing an emulsion by mixing a monomermixture with water and a surfactant, a stirrer equipped with a stirringwing; forced emulsifying devices such as homogenizer or homomixer; adevice for transport and mixing such as an in-line mixer; and a membraneemulsifying device can be mentioned.

As the emulsion described above, any dispersion like a W/O type in whichwater droplets are dispersed in a liquid of a monomer mixture and of anO/W type in which liquid droplets of a monomer mixture are dispersed inwater can be used. Preferred is an O/W type in which liquid droplets ofa dispersion has a number average dispersion particle diameter of 300 μmor less. More preferred is the one with 200 μm or less. Particularlypreferred is the one with 100 μm or less. Furthermore, the numberaverage dispersion particle diameter is preferably 0.1 μm or more.

The amount of the surfactant used for preparation of the emulsion ispreferably set at 0.5 part by mass or more and 1.6 parts by mass or lessrelative to the total amount of 100 parts by mass of a monomer mixturein any step of the polymerization. With regard to adjustment of particlesize of a polymer by successive multi-stage polymerization, the particlesize is generally adjusted according to the use amount of a surfactantduring the first stage polymerization step. However, in the presentinvention, separately from the surfactant added to a monomer mixture, asurfactant may be added to water (aqueous medium) which is added inadvance to a polymerization vessel so that the particle size of arubber-containing polymer can be reduced by use of less amount of asurfactant.

As for the polymerization initiator and chain transfer agent that areused at the time of polymerizing the monomer mixture (a) and the monomermixture (b) or additionally polymerizing the monomer mixture (c), knowncompounds can be used. As a method for adding the polymerizationinitiator and chain transfer agent, a method of adding them to any oneof an aqueous phase and a monomer phase or a method of adding them toboth phases can be mentioned.

The polymerization initiator is not particularly limited if the purposeof the present invention can be achieved. Examples of the initiatorwhich can be used include organic peroxide, inorganic peroxide, and anazo compound. Specific examples thereof include the followings: organicperoxide such as t-butyl hydroperoxide, 1,1,3,3-teteramehyl butylhydroperoxide, peroxymaleic acid t-butyl ester, cumene hydroperoxide, orbenzoyl peroxide; inorganic peroxide such as potassium persulfate orsodium persulfate; and an azo-based initiator such asazobisisobutyronitrile. They may be used either singly or in combinationof two or more types. Those initiators may be used as a commonredox-based initiator in combination with a reducing agent like sodiumbisulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbicacid, hydroxyacetic acid, ferrous sulfate, and a complex between ferroussulfate and disodium ethylenediamine tetraacetic acid.

Examples of the chain transfer agent include alkyl mercaptan with 2 to20 carbon atoms, mercaptan acids, thiophenol, and carbon tetrachloride.They may be used either singly or in combination of two or more types.For example, n-octyl mercaptan can be mentioned.

As a method for producing latex of the acrylic rubber-containing polymer(G), there is a method in which a first emulsion in which the monomermixture (a), water, and a surfactant are mixed and emulsified issupplied to a polymerization vessel for polymerization, the monomermixture (c) is supplied to the reactor for polymerization, and a secondemulsion in which the monomer mixture (b), water, and a surfactant aremixed and emulsified is further supplied to a polymerization vessel forpolymerization. In that case, it is preferable that an aqueous solutionin the reactor containing ferrous sulfate, disodium ethylenediaminetetraacetate, and sodium formaldehyde sulfoxylate dehydrate be heated toa polymerization temperature and an emulsion containing the monomermixture (a), water, and a surfactant be supplied to a polymerizationvessel.

The polymerization temperature for obtaining latex of the acrylicrubber-containing polymer (G) is, although it may vary depending on anamount or a type of a polymerization initiator or the like, 40 to 120°C. or so, for example.

The latex of the acrylic rubber-containing polymer (G) obtained by theaforementioned method can be treated, if necessary, by using a filteringdevice equipped with a filtering medium. Examples of the filteringdevice include the following filtering devices (1) to (3).

(1) a centrifuge type filtering device in which a tubular filteringmedium is disposed in a tubular filtering chamber and a stirring wing isdisposed within the filtering medium,

(2) a filtering device having a tubular element formed of wedge wirewith triangular cross section and a scraper which rotates along theouter circumference of the element, and

(3) a vibration type filtering device in which a filtering mediumexhibits a horizontal circular motion and a vertical amplitude motionrelative to a surface of the filtering medium.

Examples of the filtering medium include a web-like mesh, a porousmembrane, a membrane filter, a non-woven filter, and a wedge wirescreen. A filtering device having a web-like mesh has meshes of the samesize so that foreign substances that are larger than the mesh size canbe completely removed, and thus desirable. Examples of the mesh materialinclude a resin like nylon and polyester and metal. Among them, from theviewpoint of having non-tearibility, metal is more preferable. As forthe filtering device, a vibration type filtering device having afunction of preventing clogging of a filtering medium is preferable.

Mesh of the filtering medium for filtering the latex of the acrylicrubber-containing polymer (G) is preferably 1 to 100 μm. As the mesh ofa filtering medium decreases, more clogging is caused by coarseparticles at the time of filtering latex, thus yielding poor filtration.As such, the mesh of the filtering medium is more preferably 10 μm ormore, and more preferably 20 μm or more. Furthermore, once the coarseparticles in latex pass through a filtering device, they become a causeof fish eyes in an acrylic film. Thus, the mesh of the filtering mediumis more preferably 70 μm or less, and more preferably 60 μm or less.

When the acrylic rubber-containing polymer (G) of the present inventionis used in the form of latex, stabilization of the latex can be achievedby adding a surfactant or the like or by modifying the surface ofparticles of the acrylic rubber-containing polymer (G) by a known methodor the like. Accordingly, disruption of a stable dispersion state of thelatex, which is caused by chemical, mechanical, or physical stimulation,can be either suppressed or prevented. Examples of the surfactant whichis used for such purpose are the same as those described above.

The latex of the acrylic rubber-containing polymer (G) which is obtainedas described above can be used for various applications as it remains aslatex. It is also possible that, according to a known method likeaggregation by salting-out, acid-precipitating aggregation, freeze dry,and spray dry, the acrylic rubber-containing polymer (G) is recoveredfrom the latex followed by drying to be used as powder of the acrylicrubber-containing polymer (G). It is also possible to use is afterpelletizing the powder by melt-extrusion. Examples of the applicationsinclude a film, a spacer, an anti-blocking agent, a resin additive,particles for cosmetics, a carrier for sustained release, a fibermodifying agent, and an agent for adding functions to a resin or afiber.

When the acrylic rubber-containing polymer (G) is recovered by anaggregation method based on a salting-out treatment using a metal salt,the content of the residual metals in the acrylic rubber-containingpolymer (G) which is finally obtained is preferably 800 ppm or less.Smaller content of the residual metal is more preferable.

When a metal salt having high affinity for water like calcium, magnesiumor sodium is used as a metal salt for the aforementioned salting-outtreatment, it is preferable that the residual metal content be loweredas much as possible in the acrylic rubber-containing polymer (G).Accordingly, a whitening phenomenon occurring at the time ofimpregnating an acrylic film in boiling water, for example, can beeasily suppressed.

As for the material for forming the acrylic film of the presentinvention, the acrylic rubber-containing polymer (G) can be used eithersingly or in combination of two or more types. Furthermore, unlike theacrylic rubber-containing polymer (G), the acrylic rubber-containingpolymer (G′) which is obtained by a multi stage emulsion polymerizationnot including a step of preparing an emulsion can be also used incombination. As for the method for producing the acrylicrubber-containing polymer (G′), there can be a method in which themonomer mixture (a) for obtaining the rubber polymer (A), water, and asurfactant are admixed with one another, supplied to a polymerizationvessel, and polymerized, the monomer mixture (c) is supplied to apolymerization vessel and polymerized therein, and the monomer mixture(b), water, and a surfactant are additionally admixed with one another,supplied as an emulsion to a polymerization vessel, and polymerized.Meanwhile, the step for supplying the monomer mixture (c) forpolymerization to a polymerization vessel is a step which is performedas required.

As for the material for forming the acrylic film, the resin composition(I) in which the thermoplastic polymer (H) and the acrylicrubber-containing polymer (G) are used in combination can be used.

[Thermoplastic Polymer (H)]

The thermoplastic polymer (H) preferably contains the alkyl methacrylate(H1) unit at 50% by mass or more. The thermoplastic polymer (H) is apolymer containing the alkyl methacrylate (H1) unit having 1 to 4 carbonatoms at 50 to 100% by mass, the alkyl acrylate (H2) unit at 0 to 50% bymass, and at least one of the monomer (H3) unit other than (H1) and(H2), which has a double bond copolymerizable with them, at 0 to 50% bymass, and it is more preferably a polymer having a reduced viscosity is0.15 L/g or less. By using the thermoplastic polymer (H) in combination,surface hardness and heat resistance (in the case of a constructionapplication, matte-reduction resistance) can be improved. Therefore, Tgof the thermoplastic polymer (H) is preferably 80° C. or higher, andmore preferably 90° C. or higher. Meanwhile, the “reduced viscosity” isa value which is determined at 25° C. for a solution of 0.1 g of apolymer dissolved in 100 mL of chloroform.

Examples of the alkyl methacrylate (H1) include methyl methacrylate,ethyl methacrylate, propyl methacrylate and n-butyl methacrylate. Amongthem, methyl methacrylate is preferable. They may be used either singlyor in combination of two or more types.

Examples of the alkyl acrylate (H2) include methyl acrylate, ethylacrylate, propyl acrylate and n-butyl acrylate. Among them, methylacrylate is preferable. They may be used either singly or in combinationof two or more types.

Examples of the monomer (H3) include aromatic vinyl compounds such asstyrene, cyanovinyl monomers such as acrylonitrile, unsaturateddicarboxylic anhydrides such as maleic anhydride or itaconic anhydride,N-phenylmaleimide, and N-cyclohexylmaleimide. They may be used eithersingly or in combination of two or more types.

Content of the alkyl methacrylate (H1) unit in the thermoplastic polymer(H) is preferably 50 to 100% by mass from the viewpoint of surfacehardness and heat resistance (in the case of a construction application,matte-reduction resistance) of an acrylic film. The content is morepreferably 80 to 99.9% by mass.

Content of the alkyl acrylate (H2) unit in the thermoplastic polymer (H)is preferably 0 to 50% by mass from the viewpoint of having a filmforming property and adequate toughness for insert- and in-mold moldingof an acrylic film to be obtained. The content is more preferably 0.1 to20% by mass.

A reduced viscosity of the thermoplastic polymer (H) is preferably 0.15L/g or less, and more preferably 0.10 L/g or less from the viewpoint ofinsert moldability, in-mold moldability and a film forming property ofan acrylic resin to be obtained. Furthermore, the reduced viscosity ispreferably 0.01 L/g or more, and more preferably 0.03 L/g or more fromthe viewpoint of a filming forming property.

The method for producing thermoplastic polymer (H) is not particularlylimited, and polymerization can be performed by usual suspensionpolymerization, emulsion polymerization, or bulk polymerization.

[Resin Composition (I)]

The resin composition (I) suitably used in the acrylic film of thepresent invention contains the acrylic rubber-containing polymer (G) andthe thermoplastic polymer (H). It preferably consists of 1 to 99% bymass of the acrylic rubber-containing polymer (G) and 1 to 99% by massof the thermoplastic polymer (H). From the viewpoint of moldingwhitening resistance of an acrylic film to be obtained, the content ofthe acrylic rubber-containing polymer (G) in the resin composition (I)is more preferably 50% by mass or more, and most preferably 70% by massor more. The content of the thermoplastic polymer (H) in the resincomposition (I) is more preferably 50% by mass or less, and mostpreferably 30% by mass or less.

[Acetone Insolubles and Solubles]

The components for constituting the acrylic film of the presentinvention are preferably as follows: acetone insolubles amount W1 is 5to 70% by mass and acetone solubles amount W2 is 95 to 30% by mass inthe acrylic film, the ratio of an alkyl acrylate component in theacetone insolubles is 20% by mass or more, and the ratio of an alkylmethacrylate component in the acetone solubles is 50% by mass or more.Meanwhile, the sum of W1 and W2 is 100% by mass.

From the viewpoint of obtaining more excellent molding whiteningresistance, the acetone insolubles amount W1 in the acrylic film ispreferably 5% by mass or more, and more preferably 30% by mass or more.Meanwhile, the method for measuring the acetone insolubles is describedbelow.

From the viewpoint of molding whitening resistance, it is moreadvantageous to have a larger amount of the acetone insolubles in theacrylic film. However, the acetone insolubles amount is preferably 70%by mass or less as presence of a prepolymer at a certain amount or moreis required from the viewpoint of easy moldability.

The ratio of the alkyl acrylate component in the acetone insolubles ofthe acrylic film is preferably 20% by mass or more from the viewpoint offlexibility.

From the viewpoint of surface hardness and weather resistance, the ratioof the alkyl methacrylate component in the acetone solubles of theacrylic film is preferably 50% by mass or more.

In the acrylic film of the present invention, the total ratio of thealkyl methacrylate component and the aromatic vinyl compound componentis 80 to 0% by mass in the acetone insolubles. From the viewpoint ofhardness and weather resistance of the acrylic film, the ratio of thealkyl methacrylate component in the acetone insolubles is preferably 30%by mass or more, and more preferably 50% by mass or more. The ratio ofthe aromatic vinyl compound component in the acetone insolubles ispreferably 20% by mass or less from the viewpoint of transparency of theacrylic film.

In the acrylic film of the present invention, the total ratio of thealkyl acrylate component and the aromatic vinyl compound component is 50to 0% by mass in the acetone solubles. From the viewpoint of flexibilityof the acrylic film, the ratio of the alkyl acrylate component in theacetone solubles is preferably 5% by mass or more. The ratio of thearomatic vinyl compound component in the acetone solubles is preferably20% by mass or less from the viewpoint of transparency of the acrylicfilm.

The heat deflection temperature of the acrylic film of the presentinvention is preferably 70° C. or higher. When the heat deflectiontemperature is 70° C. or higher, it is unlikely to have an occurrence ofsurface roughness after heating a laminate which has an acrylic film onits surface. Furthermore, when the heat deflection temperature is 80° C.or higher and a laminate obtained after a surface roughening treatment,which is achieved by an embossing processing or the like of acrylic filmsurface, is subjected to thermal processing, deterioration of adecoration property which is caused by matte-reduction of an embossedsurface can be suppressed, and thus it can have a high industrial value.

[Additives]

The acrylic film of the present invention may contain, as necessary,common additives such as stabilizers, lubricants, processing aids,plasticizers, anti-impact agents, foaming agents, fillers, antibacterialagents, fungicides, mold releasing agent, antistatic agents, coloringagents, ultraviolet absorbing agents and photostabilizers.

In particular, from the viewpoint of protecting a base, it is preferableto add an ultraviolet absorbing agent for providing weather resistance.As an ultraviolet absorbing agent, known ones can be used and also acopolymerization type can be used. A molecular weight of the ultravioletabsorbing agent used is preferably 300 or more, and more preferably 400or more. An ultraviolet absorbing agent with a molecular weight of 300or more can be used to prevent mold contamination with the vaporizedultraviolet absorbing agent during vacuum- or press molding in aninjection mold. Generally, an ultraviolet absorbing agent with a highermolecular weight can more significantly minimize long-term bleed-outafter processing into a film state and thus allow ultraviolet absorbingperformance to be maintained for a longer time than that with a lowermolecular weight. Furthermore, an ultraviolet absorbing agent with amolecular weight of 300 or more can reduce vaporization of theultraviolet absorbing agent in the period from extrusion of the acrylicfilm from a T die to cooling by a cooling roll. Therefore, there mayremain an adequate amount of the ultraviolet absorbing agent to exhibitgood performance. It also can eliminate the problem that the vaporizedultraviolet absorbing agent is recrystallized and grown over time on achain suspending the T die over the T die or on an exhaust hood, andfinally dropped on a film, leading to defects in the outer appearance ofthe film.

The type of the ultraviolet absorbing agent is not particularly limited,but benzotriazoles with a molecular weight of 400 or more, or triazineswith a molecular weight of 400 or more can be preferably used. Specificexamples of the former include TINUVIN 234 (trade name) manufactured byCiba Specialty Chemicals and ADEKA STAB LA-31 (trade name) manufacturedby Asahi Denka Co., Ltd. Specific examples of the latter include TINUVIN1577 (trade name) manufactured by Ciba Specialty Chemicals.

The addition amount of the ultraviolet absorbing agent is preferably 0.1to 10 parts by mass per 100 parts by mass of the acrylicrubber-containing polymer (G) or the resin composition (I). From theviewpoint of improving weather resistance of the acrylic film, theaddition amount of the ultraviolet absorbing agent is more preferably0.5 part by mass or more, and most preferably 1 part by mass or more.From the viewpoint of roll contamination during film forming, chemicalresistance and transparency of the acrylic film, the addition amount ofthe ultraviolet absorbing agent is preferably 5 parts by mass or less,and most preferably 3 parts by mass or less.

The photostabilizer may be selected from those well-known in the art,but for improving not only light stability but also chemical resistanceof the acrylic film, a radical scavenger such as a hindered aminephotostabilizer is preferably used. For example, in the case of adhesionof a hair dressing material on the acrylic film, appearance variationcan be significantly improved by the photostabilizer, resulting inhigher industrial utility.

The addition amount of the hindered amine photostabilizer is preferably0.01 to 5 parts by mass per 100 parts by mass of the acrylicrubber-containing polymer (G) or the resin composition (I). From theviewpoint of improving light stability and chemical resistance of theacrylic film, the addition amount of the hindered amine photostabilizeris more preferably 0.1 part by mass or more, and most preferably 0.2part by mass or more. From the viewpoint of roll contamination duringfilm forming, the addition amount of the hindered amine photostabilizeris preferably 2 parts by mass or less, and most preferably 1 part bymass or less.

These particular ultraviolet absorbing agent and the hindered aminephotostabilizer can be combined to provide an acrylic film particularlysuitable for vehicle applications.

As for a method of adding the aforementioned additives, there is amethod in which additives are supplied together with a componentcontaining the acrylic rubber-containing polymer (G) or the resincomposition (I) to an extruder for forming an acrylic film and a methodin which a mixture preliminarily prepared by adding the additives to acomponent containing the acrylic rubber-containing polymer (G) or theresin composition (I) is kneaded and mixed by using various kneaders.Examples of a kneader used in the latter procedure include common singlescrew extruders, twin screw extruders, Banbury mixers and roll kneaders.

[Method for Producing Acrylic Film]

The method for molding an acrylic film by using the acrylicrubber-containing polymer (G) is not particularly limited, and examplesthereof include a known method including melt extrusion processes suchas solution casting, T die method, and inflation method. Among them,from the viewpoint of economical reason, T die method is mostpreferable.

The acrylic film of the present invention can be produced by a methodincluding a step of obtaining powder of the acrylic rubber-containingpolymer (G) after filtration by passing latex of the acrylicrubber-containing polymer (G) through a filtering medium with 1 to 100μm mesh and a step of producing a film by melt extrusion of an acrylicresin composition containing powder of the acrylic rubber-containingpolymer (G) from a T die. Examples of the acrylic resin compositioncontaining powder of the acrylic rubber-containing polymer include theresin composition (I) described above.

The acrylic film of the present invention can be also produced by amethod including a step of producing a film by melt extrusion of anacrylic resin composition containing the acrylic rubber-containingpolymer (G) from a T die and a step of sandwiching the film between twopieces selected from a metal roll, a non-metal roll, and a metal belt.

Meanwhile, when conducting melt extrusion by T die method, it is alsopreferable to perform extrusion while filtering an acrylic resin in amolten state by using a screen mesh with 200 mesh or more (=75 μm orless). As for the screen mesh, one screen or two or more screens areused. It is also possible to use two or more screens of a separate typewith different mesh.

The acrylic resin composition extruded from a T die is formed into afilm by a collector equipped with a cooling roll. The method for coolingthe molten resin is not particularly limited, and examples thereofinclude a method of forming a film by contact with one metal roll; and amethod of forming a film by sandwiching between a plurality of metalroll, non-metal roll, and/or metal belt.

For the method of forming a film by cast contact of the molten acrylicresin composition with one metal roll, it is preferable to use a T diehaving slit width of 1 mm or less from the viewpoint of easily producingan acrylic resin film having specific heating shrinkage rate.

Meanwhile, when a method of forming a film by sandwiching between aplurality of metal roll, non-metal roll, and/or metal belt is used,surface smoothness of an acrylic resin film to be obtained can beimproved so that printing losses can be suppressed at the time ofperforming printing on the acrylic resin film.

Examples of metal rolls include metal mirror touch rolls; and rolls usedin a sleeve touch manner consisting of a metal sleeve (metal film pipe)and a molding roll, described in JP 08-155995 or WO 97/28950. Examplesof non-metal rolls include touch rolls made of, for example, siliconerubber. Examples of a metal belt include a metal endless belt. Aplurality of these metal rolls, non-metal rolls and metal belts may beused in combination.

According to the method of forming a film by sandwiching between aplurality of metal roll, non-metal roll, and/or metal belt as describedabove, an acrylic resin composition after melt extrusion is sandwichedsubstantially without a bank (resin deposit) and is plane-transferredsubstantially without rolling to form a film. When forming a filmwithout forming a bank (resin deposit), an acrylic resin composition isplane-transferred in the course of cooling without rolling, so that aheat shrinkage ratio of the acrylic resin film thus formed can bereduced. As a result, an acrylic resin film having a specific heatshrinkage ratio can be easily produced.

Meanwhile, when a film is formed by using a plurality of metal roll,non-metal roll, and/or metal belt, it is also possible that the surfaceof at least one of the metal roll, non-metal roll, and metal belt issubjected to a shape processing like emboss processing and mattprocessing, and then shape transferring is performed on a single surfaceor both surfaces of the acrylic resin film.

[Surface Processing]

For giving a decorative property to various bases, the acrylic film ofthe present invention can be also used after having printing accordingto a suitable printing method, if necessary. In such case, it ispreferable to use an acrylic film having one surface treated byprinting. It is also preferable, from the viewpoint of protecting aprinted surface and providing a high quality feel to a product, to havethe printed surface placed on an adhesion surface of a base resin.Furthermore, when it is used as a substitute for transparent coating fortaking advantage of color of a base, the acrylic film can be used in atransparent state. In particular, for an application in which color of abase is preserved, the acrylic film of the present invention is betterthan a polyvinyl chloride film or a polyester film in terms oftransparency, depth feel, and high quality feel.

Furthermore, the acrylic film containing the acrylic rubber-containingpolymer (G) of the present invention has few fish eyes in the film, andthus it has less printing losses even when gravure printing such as palecolor wood grain pattern under a lower printing pressure and metallicand jet-black printing, by which printing losses particularly tend tooccur, are performed, and has a high level printing property that isnever obtained with an acrylic film in which a rubber-containing polymerknown in a related art is used as a raw material for film.

Furthermore, the acrylic film of the present invention may be used, ifnecessary, after a matt reduction treatment like embossing processing orcoloration processing.

<Laminate Film>

The acrylic film of the present invention may be used as a laminate filmin which a layer of at least one resin selected from a thermoplasticresin, a thermosetting resin, and a photocurable resin is laminated onone surface or both surfaces of the film. Examples of the thermoplasticresin include a polyvinylidene fluoride resin, an ABS resin, an ASresin, a polystyrene resin, a polycarbonate resin, a vinyl chlorideresin, an acrylic resin, a polyester resin, and a resin containing themat 50% by mass or more. Examples of the thermosetting resin include aphenol resin, an epoxy resin, a melamine resin, a urea resin, and aresin containing them at 50% by mass or more. Examples of thephotocurable resin include a thermoplastic resin having a radicalpolymerizable unsaturated group in a side chain and a resin containing aphotopolymerization initiator.

As a method for obtaining a laminate film, a known method like thermallamination, dry lamination, extrusion lamination, co-extrusion, andcoating can be used.

<Laminated Injection Molded Article>

The acrylic film or the laminate film of the present invention can beused as a laminated injection molded article which is obtained bylamination on an injection molded article. As a method for obtaining alaminated injection molded article, a known molding method like aninsert molding method in which an acrylic film or a laminate film whichhas been previously subjected to a shape processing is inserted to amold for injection molding and an in-mold molding method in whichextrusion molding is performed in a mold after vacuum molding can beused.

The in-mold molding method is preferable in terms of workability andeconomical property as it allows performing both film molding andinjection molding in one step. The heating temperature is preferably atemperature which is the same or higher than the softening point of theacrylic film. The lower limit of the heating temperature is generallydetermined by thermal properties of a film or shape of a molded article,but it is generally 70° C. or higher. Furthermore, when the heatingtemperature is extremely high, the surface appearance of a moldedarticle is deteriorated or poor releasing property is obtained. Thus,although it is determined by thermal properties of a film or shape of amolded article, the upper limit of the heating temperature is generally170° C. or lower. According to an in-mold molding method, a threedimensional shape is given to a resin material by vacuum molding, andaccording to melt-integralization of the acrylic film and base resin byinjection molding, an acryl-laminated molded article having an acrylicfilm on a surface layer can be obtained.

Examples of the resin as a base for injection molding with an acrylicfilm for insert molding or in-mold molding include an ABS resin, an ASresin, a polystyrene resin, a polycarbonate resin, a vinyl chlorideresin, an acrylic resin, a polyester resin, and a resin containing themat 50% by mass or more.

If necessary, the acrylic film or laminate film of the present inventionmay be subjected to a surface treatment for having various functions,and examples thereof include the following treatments: a printingtreatment by silk printing or ink jet printing, metal deposition,sputtering, or wet type plating treatment for having metallic feel orpreventing reflection, a surface hardening treatment to improve surfacehardness, a water-repellent treatment or a treatment for formingphotocatalyst layer to prevent fouling, an anti-static treatment for thepurpose of preventing dirt adhesion or cutting electromagnetic wave,forming an anti-reflection layer, and an anti-glare treatment.

Examples of an industrial application of the laminated injection moldedarticle which includes an acrylic film or a laminate film of the presentinvention include the followings: an automobile component likeautomobile exterior or automobile interior decoration; a constructionalcomponent like wall material and window frame; household goods likedishware and toy; a home appliance component like housing for vacuumcleaner, housing for television, and housing for air conditioner;interior component; ship component; and electronic communication devicelike Personal Computer housing and housing for a cellular phone.

EXAMPLES

Hereinbelow, the present invention is described in greater detail inview of the examples. Meanwhile, “parts” and “%” in Examples andComparative Examples indicate “parts by mass” and “% by mass”,respectively, and abbreviated symbols/abbreviations are as described inTable 1.

Furthermore, each measurement value of Examples was obtained by themethod shown below.

[Evaluation 1] Particle Diameter of Dispersion Phase of Emulsion:

A single drop of emulsion was added on a preparative glass and themagnification ratio was fixed to a ratio at which at least tendispersion phase particles can be observed in an observation range usingan optical microscope. The number of every dispersion phase particlesthat can be observed in an observation range was counted, and anapproximate particle size of each particle was obtained. Based on theobtained results, the number average dispersion particle diameter (μm)of the dispersion phase was obtained.

[Evaluation 2] Mass Average Particle Diameter of Polymer Particles:

A mass average particle diameter of the polymer particles was obtainedby measuring the polymer latex, which has been obtained by emulsionpolymerization, based on a dynamic light scattering method using a lightscattering photometer (FPAR-1000) manufactured by Otsuka ElectronicsCo., Ltd.

[Evaluation 3] Filtering Property of Latex:

The polymer latex which has been obtained by emulsion polymerization wasstirred well, and immediately thereafter, 100 g of the latex was weighedand filtered by using a tubular filtering device provided with nylonmesh having 270 mesh (mesh of 54 μm) (KST-47 manufactured by ADVANTEC,effective filtering area of 12.5 cm²). Then, the amount of the latex (g)filtered for 30 seconds was measured. Expression was made in terms ofthat amount (g/30 seconds).

[Evaluation 4] Amount of Acetone Insolubles in Acrylic Film:

1% by mass acetone solution containing 0.5 g of an acrylic film wasprepared. After keeping it for 24 hours at room temperature (25° C.),centrifuge was performed at 16000 rpm for 90 minutes to remove thesupernatant. The obtained wet product was dried at a reduced pressure(vacuum level of 47 mmHg) at room temperature for 18 hours. When themass before extraction was Wi (g) and the mass of the dried product isWd (g), W1(%) calculated according to the following calculation formulawas defined as an amount of acetone insolubles.W1(%)=Wd (g)/Wi (g)×100.

[Evaluation 5] Analysis of Components:

1% by mass acetone solution containing 0.5 g of an acrylic film wasprepared. After keeping it for 24 hours at room temperature (25° C.),centrifuge was performed at 16000 rpm for 90 minutes to remove thesupernatant. The obtained wet product was dried at a reduced pressure(vacuum level of 47 mmHg) at room temperature for 18 hours. The driedresiduals Wp (g) which have been obtained as described above weresubjected to pyrolysis gas chromatography to measure the mass Wa (g) ofthe alkyl acrylate component. “Wa/Wp×100” was determined as the ratio(%) of the alkyl acrylate component in acetone insolubles. Further,acetone was evaporated from the aforementioned supernatant, and driedresiduals We (g) which have been obtained after drying at a reducedpressure (vacuum level of 47 mmHg) at room temperature for 18 hours weresubjected to pyrolysis gas chromatography to measure the mass Wm (g) ofthe alkyl methacrylate component. “Wm/Wc×100” was determined as theratio (%) of the alkyl methacrylate component in acetone solubles.

[Evaluation 6] Number of Fish Eyes:

From a 1 m² film having a thickness of 50 μm, a length of 1 m, and awidth of 1 m, the number of fish eyes with a size of 0.001 mm² orgreater to have a light transmission ratio of 75% or less for lighthaving a wavelength of 400 to 1100 nm was measured by usingB-LSC-6276-MR (manufactured by MEC Co., Ltd.).

Example 1

[1. Preparation of Monomer Mixture]

The compound of a type and an amount shown in Table 2 was injected toeach vessel equipped with a stirrer followed by stirring to obtain amonomer mixture.

[2. Polymerization Reaction]

To a vessel 1 containing the monomer mixture (a-1), 5.8 parts ofdeionized water and 0.7 part of a surfactant S were added followed bystirring to prepare the first emulsion (a-1e). Part of the emulsion wassampled and the particle diameter of the emulsion dispersion phase wasmeasured and described in Table 3. Next, to a polymerization vesselequipped with a cooler, 147 parts of deionized water and 0.1 part of asurfactant S were added. After raising the temperature to 75° C., amixture containing 5 parts of deionized water, 0.20 part of sodiumformaldehyde sulfoxylate dehydrate, 0.0001 part of ferrous sulfate, and0.0003 part of EDTA was added all at once to the polymerization vessel.Subsequently, the air inside the polymerization vessel was replaced withnitrogen, and while stirring the mixture under nitrogen atmosphere, theemulsion (a-1e) was added dropwise to the polymerization vessel for 9minutes. After that, the reaction was additionally continued for 15minutes to complete the polymerization. As a result, latex of the rubberpolymer (A-1) was obtained.

Subsequently, the monomer mixture (c-1) in a vessel 2 was added dropwiseto the aforementioned polymerization vessel for 90 minutes. Aftercontinuing the reaction for 60 minutes, latex of the polymer (A-1-c-1)was obtained. Furthermore, the monomer mixture (c-2) in a vessel 3 wasadded dropwise to the aforementioned polymerization vessel for 45minutes. After continuing the reaction for 60 minutes, latex of thepolymer (A-1-c2) was obtained.

Subsequently, to a vessel 4 containing the monomer mixture (b-1), 25parts of deionized water and 0.3 part of a surfactant S were addedfollowed by stirring to prepare the second emulsion (b-1e). Part of theemulsion was sampled and the particle diameter of the emulsiondispersion phase was measured and described in Table 3. It was thenadded dropwise to the aforementioned latex for 140 minutes. Aftercontinuing the reaction for 60 minutes, latex of the acrylicrubber-containing polymer (G-1) was obtained.

[3. Filtration of Latex]

By using part of the acrylic rubber-containing polymer (G-1) in thelatex, the mass average particle diameter of the polymer particles andthe filtering property of the latex were measured, and the results areshown in Table 3. Furthermore, after filtering the latex by using avibration type filtering device equipped with 270 mesh (average mesh: 54μm) made of SUS as a filtering medium, it was subjected to salting-outin an aqueous solution containing 3 parts of calcium acetate. Afterrecovery with washing and drying, the rubber-containing polymer (G-1)was obtained in powder form.

[4. Production and Evaluation of Film]

75 parts of the acrylic rubber-containing polymer (G-1) which has beenobtained from above and 25 pars of the thermoplastic polymer (H-1)[MMA/MA copolymer (MMA/MA=99/1 (mass ratio), reduced viscosityηsp/c=0.06 L/g)] were added with, as an additive, 1.4 parts of “TINUVIN234” manufactured by Ciba Specialty Chemicals Inc., 0.3 part of “ADKSTAB LA-67” manufactured by ADEKA CORPORATION, and 0.1 part of “IRGANOX1076” manufactured by BASF and admixed with each other by using aHenschell mixer. The mixture was supplied to a degassing type extruder(PCM-30 manufactured by Ikegai Corp.) which has been heated to 240° C.followed by kneading to obtain pellets of the resin composition (I-1).The resulting pellets were dried for 24 hours at 80° C. and, by using a40 mmϕ non-vent screw type extruder (L/D=26) equipped with a T diehaving a width of 300 mm, the film (F-1) with a thickness of 50 μm wasformed as a film at conditions including a cylinder temperature of 200°C. to 240° C., a T die temperature of 250° C., and a cooling rolltemperature of 70° C. Then, the amount of acetone insolubles in thefilm, the ratio of the alkyl acrylate component in the acetoneinsolubles, the ratio of the alkyl methacrylate component in the acetonesolubles, and the number of film fish eyes were measured and describedin Table 3.

Example 2

Latex of the acrylic rubber-containing polymer (G-2) was obtained in thesame manner as Example 1 except that a monomer mixture shown in Table 2was used.

By using part of the acrylic rubber-containing polymer (G-2) in thelatex, the mass average particle diameter of the polymer particles andthe filtering property of the latex were measured, and the results areshown in Table 3.

Furthermore, after filtering the latex by using a vibration typefiltering device equipped with 400 mesh (average mesh: 34 μm) made ofSUS as a filtering medium, it was subjected to salting-out in an aqueoussolution containing 3 parts of calcium acetate. After recovery withwashing and drying, the acrylic rubber-containing polymer (G-2) wasobtained in powder form.

The film (F-2) with a thickness of 50 μm was formed as a film in thesame manner as Example 1 except that 100 parts of the aforementionedacrylic rubber-containing polymer (G-2) were used instead of 75 parts ofthe acrylic rubber-containing polymer (G-1) and 25 pars of thethermoplastic polymer (H-1). The resulting film was subjected to thesame evaluation as Example 1 and the evaluation results shown in Table 3were obtained. Since latex of the acrylic rubber-containing polymer(G-2) was filtered through a mesh with mesh size of 34 μm, the number offish eyes was low in the film.

Comparative Example 1

Latex of the acrylic rubber-containing polymer (G′-1) was obtained inthe same manner as Example 1 except that, as the monomer mixture (b-1),a monomer mixture in which 57 parts of MMA, 3 parts of MA, 0.248 part ofn-OM, and 0.075 part of t-BHP were mixed was used and the monomermixture was directly added dropwise to a polymerization vessel withoutbeing emulsified in water.

By using part of the acrylic rubber-containing polymer (G′-1) in thelatex, the mass average particle diameter of the polymer particles andthe filtering property of the latex were measured, and the results areshown in Table 3. According to Comparative Example 1, the monomermixture (b-1) was not prepared as an emulsion so that there are lots ofcoarse particles in latex, yielding a poor filtering property.

Furthermore, after filtering the latex by using a vibration typefiltering device equipped with 270 mesh (average mesh: 54 μm) made ofSUS as a filtering medium, it was subjected to salting-out in an aqueoussolution containing 3 parts of calcium acetate. After recovery withwashing and drying, the acrylic rubber-containing polymer (G′-1) wasobtained in powder form.

Next, pellets of the resin composition (I′-1) were obtained in the samemanner as Example 1 except that the acrylic rubber-containing polymer(G′-1) was used instead of the acrylic rubber-containing polymer (G-1).The pellets were dried at 80° C. for 24 hours and, according to the samemethod as Example 1, the film (F′-1) with a thickness of 50 μm wasprepared as a film. The resulting film was subjected to the sameevaluation as Example 1 and the evaluation results shown in Table 3 wereobtained. Since the monomer mixture (b-1) was not supplied as anemulsion to the polymerization vessel, the number of fish eyes was highin the film.

Comparative Example 2

Latex of the acrylic rubber-containing polymer (G′-2) was obtained inthe same manner as Example 1 except that the monomer mixture (a-1) wasdirectly added dropwise to a polymerization vessel without beingemulsified in water.

By using part of the acrylic rubber-containing polymer (G′-2) in thelatex, the mass average particle diameter of the polymer particles andthe filtering property of the latex were measured, and the results areshown in Table 3. According to Comparative Example 2, the monomermixture (a-1) was not prepared as an emulsion so that the filteringproperty of latex was poor.

Furthermore, after filtering the latex by using a vibration typefiltering device equipped with 270 mesh (average mesh: 54 μm) made ofSUS as a filtering medium, it was subjected to salting-out in an aqueoussolution containing 3 parts of calcium acetate. After recovery withwashing and drying, the acrylic rubber-containing polymer (G′-2) wasobtained in powder form.

Next, pellets of the resin composition (I′-2) were obtained in the samemanner as Example 1 except that the acrylic rubber-containing polymer(G′-2) is used instead of the acrylic rubber-containing polymer (G-1).The pellets were dried at 80° C. for 24 hours and, according to the samemethod as Example 1, the film (F′-2) with a thickness of 50 μm wasprepared as a film. The resulting film was subjected to the sameevaluation as Example 1 and the evaluation results shown in Table 3 wereobtained. Since the monomer mixture (a-2) was not prepared as anemulsion, the number of fish eyes was high in the film.

TABLE 1 Abbreviated symbols/abbreviation Compound name MMA Methylmethacrylate BA Butyl acrylate MA Methyl acrylate AMA Allyl methacrylateBDMA 1,3-Butylene glycol dimethacrylate t-BHP t-Butyl hydroperoxide CHPCumene hydroperoxide n-OM n-Octyl mercaptan Surfactant S Sodiumpolyoxyethylene alkyl ether phosphate [product name: PHOSPHANOLRS-610NA, manufactured by TOHO Chemical Industry Co., Ltd.] EDTADisodium ethylenediamine tetraacetate

TABLE 2 Comparative Comparative Example 1 Example 2 Example 1 Example 2Monomer Compound Parts by Compound Parts by Compound Parts by CompoundParts by Vessel mixture name mass name mass name mass name mass Vessel 1Monomer MMA 0.3 MMA 0.3 MMA 0.3 MMA 0.3 mixture BA 4.5 BA 4.5 BA 4.5 BA4.5 (a-1) AMA 0.05 AMA 0.05 AMA 0.05 AMA 0.05 BDMA 0.2 BDMA 0.2 BDMA 0.2BDMA 0.2 CHP 0.025 CHP 0.025 CHP 0.025 CHP 0.025 Vessel 2 Monomer MMA9.6 MMA 9.6 MMA 9.6 MMA 9.6 mixture BA 14.4 BA 14.4 BA 14.4 BA 14.4(c-1) AMA 0.25 AMA 0.25 AMA 0.25 AMA 0.25 BDMA 1 BDMA 1 BDMA 1 BDMA 1CHP 0.016 CHP 0.016 CHP 0.016 CHP 0.016 Vessel 3 Monomer MMA 6 MMA 6 MMA6 MMA 6 mixture MA 4 BA 4 MA 4 MA 4 (c-2) AMA 0.075 AMA 0.075 AMA 0.075AMA 0.075 CHP 0.013 CHP 0.013 CHP 0.013 CHP 0.013 Vessel 4 Monomer MMA57 MMA 55.2 MMA 57 MMA 57 mixture MA 3 BA 4.8 MA 3 MA 3 (b-1) n-OM 0.248n-OM 0.22 n-OM 0.248 n-OM 0.248 t-BHP 0.075 t-BHP 0.075 t-BHP 0.075t-BHP 0.075 Rubber-containing polymer G-1 G-2 G′-1 G′-2

TABLE 3 Comparative Comparative Example 1 Example 2 Example 1 Example 2Monomer mixture (a-1) Emulsified Emulsified Emulsified Not emulsifiedMonomer mixture (b-1) Emulsified Emulsified Not emulsified EmulsifiedMesh of filtering medium (μm) 54 34 54 54 [Evaluation 1] Particlediameter of dispersion phase of first 50 45 50 — emulsion (μm)[Evaluation 1] Particle diameter of dispersion phase of second 80 85 —75 emulsion (μm) [Evaluation 2] Mass average particle diameter ofpolymer 123 120 125 122 particles (nm) [Evaluation 3] Filtering propertyof latex (g/30 seconds) 79 85 54 28 [Evaluation 4] Amount of acetoneinsolubles in acrylic film 50 58 53 52 (%) [Evaluation 5] Ratio of alkylacrylate component in acetone 32 30 35 34 insolubles (%) [Evaluation 5]Ratio of alkyl methacrylate component in 94 90 91 95 acetone solubles(%) [Evaluation 6] Number of fish eyes (fish eye/m²) 125 83 233 1285

INDUSTRIAL APPLICABILITY

The laminated injection molded article including the acrylic film or thelaminate film of the present invention can be applied for an automobilecomponent, a construction material component, household goods, a homeappliance component, an interior member, a ship member, a PersonalComputer housing, an electronic communication device, or the like.

The invention claimed is:
 1. A method for producing an acrylicrubber-containing polymer (G) used for an acrylic film, the methodcomprising multi-stage polymerization steps including the followingsteps (1) and (2): (1) a first stage polymerization step in which afirst emulsion having a monomer mixture (a) containing 20% by mass ormore of alkyl acrylate emulsified in water is supplied to apolymerization vessel, and (2) a second stage polymerization step inwhich a second emulsion having a monomer mixture (b) containing 50% bymass or more of alkyl methacrylate emulsified in water is supplied tothe polymerization vessel after the first polymerization step, wherein anumber average particle diameter of a dispersion phase is 300 μm or lessfor the first emulsion and the second emulsion, respectively, and anamount of a surfactant used for preparation of the emulsions is set at0.5 parts by mass or more and 1.6 parts by mass or less relative to thetotal amount of 100 parts by mass of a monomer mixture in anypolymerization steps of the multistage polymerization steps, wherein atleast one polymerization step (3) is included between the step (1) andthe step (2), and the polymerization step (3) does not include anemulsifying step.
 2. The method according to claim 1, wherein the numberaverage particle diameter of a dispersion phase is 200 μm or less forthe first emulsion and the second emulsion, respectively.
 3. The methodaccording to claim 1, wherein the number average particle diameter of adispersion phase is 100 μm or less for the first emulsion and the secondemulsion, respectively.
 4. The method according to claim 1, wherein thenumber average particle diameter of a dispersion phase is 0.1 μm or morefor the first emulsion and the second emulsion, respectively.
 5. Themethod according to claim 1, wherein the first emulsion having themonomer mixture (a) contains 30 to 99.9% by mass of alkyl acrylateemulsified in water.
 6. The method according to claim 1, wherein thesecond emulsion having the monomer mixture (b) contains 60 to 100% bymass of alkyl methacrylate emulsified in water.